SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85463002e65fadd9f25b7f5a30f9a4ea7df8edd489c04654a847959690aa957e' 
  AND token = 'V6G7MzwUIKv0HHSdiJASeuz6j1RuINcNzbPxBJ/5DfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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