SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12a3a01583fa29548ddabf0b07b3d41a61e57a0fafad1ce8afdf1d47e13ec07e' 
  AND token = 'r3kE/tIUoTE8CEVyjkOtX8tWcMBxCTgTVkRtjEOAYC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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