SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc2ca128011980604f2311ccf7f59290dfa3dc4a2984d50ba68dcd326a6737d5' 
  AND token = 'x1tAdbbd38p5JY8VQnBFI6j2QJFEdlY42GUF9StfO90=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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