SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b51c1d55817018b3c30b0ac4b9c70b274cd648dbf69c546754122934a626a786' 
  AND token = 'ZM+I8fnGXzGTdd1jKFCKU1Q6s9byLTL+ssKVVAX1dZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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