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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adfc2ac0a2e8e8a5ef5e1b8584f3d93fdd6548b0cfe878f0dbb359928a65c398' 
  AND token = 'rlUUZzJuD5rY3Nk/7i++rLEs8Mc93TifwJeE5feY728=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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