SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '796523eb5689f6c1bc1171f8cd88643b074a1c333b39f5c7931854d770601c66' 
  AND token = 'Ag3rFSDoKxbzmmGmG7wVbO9ctfv9/aPHM1EtAf47osE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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