SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2739dba17fb4dc0b48640d706048b8246cfae87f0894f51cdf03abc148ab3c67' 
  AND token = 'IMbcXW+yyhBzLtPAAGvHCgjVTq5zKn5CbzHE5Bywxes=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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