SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bbc615d98343b12be9676a0f4b2e57a0eee983edc980a45a2dc39c0bfff21b5' 
  AND token = 'OUeyQJOXpIkedqgkPXI6YCT+bgzwvJN1/uMhSV3p9rY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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