SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b2b4593574c145baaee309e42ccf35c48d653d303121009c9328c96b42506ae4' 
  AND token = 'jKP5jmsjDxDTN3MMtjYLF2r+2TK1zPw6nT8a2IZuUVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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