SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffc94a588ef208d1a682a3f095f58374e55d64ecb46fcd034afa8598ec78008b' 
  AND token = 'cvVxMPQLzF+dYwrMV70BYzyTfROig7FGkPlEq/N9hMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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