SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'fe8839dea2981bf68b89d1266aa22cd0294c4a460ee9aacd8ae5311c1a4fb4a2' 
  AND token = '2NE7oOKfgkEE/7ymvuuq9wEeswFKV2Fr6NP8kEjQ3Wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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