SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2719e0e6b93d76afc3c2c0b2cd7b12fa4b0d1d054931544bdb27ad42fa4458ed' 
  AND token = 'oMr1Yd2JYAKAtqqSZ8fjZsUW6G4mzD8JXpQ2VlC6LMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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