SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8343378b6b2f0596e164d43ab3a1adb17cd0261b0ec85a8ebadc3a267572df43' 
  AND token = 'er3dgH9vqXiXs9UmOAPAye5dqHEbIYRgEpHTo52oBFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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