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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c75e6d41a34421bc337eff78d82f114cb1f973cd012a6dc0c9f60e91469ff4ca' 
  AND token = 'l7rG5hSRXEh+7SfGjeXwH4/R2z04rCqQ8vGC3qbDNiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}