SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c43bb97bc1da6ff95b29d1fa6fd5414b1a4aad129018170983ff86bb99e2f51' 
  AND token = '3OADAWikVE2P3N9ZIB/ReklQomA1lf2CO4dF/BxSWko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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