SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0c0a46db8f569bf5a85331a30b95d72b48eaeca556df2d1cc9d231414a93747' 
  AND token = 'F+uUBMtnDi2QehEdgpLfYcYxXYGd7dBb/+FTUQQWxBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}