SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e75c628fc041d6f0f67ca53accab2a0983e8ff0e540bc92cdf53842e1ab2288d' 
  AND token = 'wzEXhRgQSxqPcZTHiE58vz2qtFMPdIKD5y+WlhXxyCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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