SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2cdfc0146e01de264079ad94e9bd047810fbf0f3d843f12ade2636c1ce5198f2' 
  AND token = 'euJD9RePPKt4KMX3Ix7JBKgWt4CP2jKujkL678XysE0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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