SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b2c1bbc65ca103270bd22950cf626677f01599c4ed5ab3114dddea4d51611d80' 
  AND token = 'B2x9r81bawgSzodYL1C/KfVbU6GFrAVfVyExM/+lJXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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