SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c6906f5b0d78822a5d1fab6f692c3701f0d0025504e7bb50ed37f76d06954c7' 
  AND token = 'DNLM8vMP2EKLtSEbylXVR8mqAVxXUb+ewlEDhm+3uyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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