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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe61dfefbc8bf4b5aa365d2d7503d73c5c23dc160598ecf3eff5ddce55d041f2' 
  AND token = 'nfb8gvbzWRxbguYiDPWaozkgYHzhdpqKskZgagpy5Qc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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