SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66f81bce2cd76106147b006e2d481b336f40c608df8d7c32ccbfce2dd7c1fefb' 
  AND token = '+bF4oAazCvebH1eas3v+85xTXfMDw0Lyw0sfFvza2UA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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