SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7c9a8b0aeda644077b60bf5cc10d6941809efabdfa4861e1899b618e41589c6' 
  AND token = 'HCMpBj+KA/Y1K2lAVlvgiZmfWv3lz/sAUL/R3Tc3Syo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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