SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b1f6c0de67a8153c63268e2fac90ee6ab2951c37c754922251b2dabbbcb875a' 
  AND token = '+89di7l6BYmXegdN0/CY4E3ZdmyyAKyAiA7ksfgZRok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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