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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8f9422fe063770159a9479d65500974520258950004aa5866e9c8620be9aa06' 
  AND token = 'uEVZv9RacNyhHJvytuY2iCc59agvbHcmkHGlCJL6I8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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