SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e443ea070a9e5f660d652304440b753b3c0b375e311436a19b04897bb0055f09' 
  AND token = '3Zt9+lZ0wQgqyqOzUV5xzKmH2t3nISJI3T4Z8SEUG2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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