SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '831f3c3e56b617f3fdb2701ec8a02f20181bed0f09bfe2889ef9a6136252e82c' 
  AND token = 'CmBDppJ1kTLLORTDCI3GkOfTcuKIQMTwPRAb2pj4LRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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