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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b3b0fc6fb004de1d2cfd69b6afa6a3ebf3bd0bd6a1020ab31df4b41729587e9' 
  AND token = 'gIIiIsBAiq3QArEukiRaqiJqZBdfO+7TiqZgV6QAuLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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