SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b267b2c73442b1ccca62855642721768c330a61fcb372950a3e250e3ba516acb' 
  AND token = 'iClb/TaYyeSswjzUYb+RGPPLUJyjka/emUKXZe3TksQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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