SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'cb4a56930ec1ab28386eadb2a06212556f7a7e81a5ff714021c389eb90afb297' 
  AND token = '/f2VauXegzwo8ebpypGr2v8DKMqS8160QNVMuN0/hGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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