SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c9a8154d06ce1551222bb5a91b60396638d8f1b421c36d2891272192f5b8c9' 
  AND token = '7j3FU/N1gGVBCSyucWKhVSA2PtlT+p86cwC8eFJL3Qg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00105

JSON explain

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