SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c3c0c7002ee84e4d2bc21fad22359253497685db919e7f664729b973e1a6d8f4' 
  AND token = 'SzhtPzTkIxic559lSft/fXtjYD35hyVXpMW+04a8uAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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