SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f650be38c6bfce773189ccfab20173d3574a4863929ae4c79483a94780f5da44' 
  AND token = 'ICrmjQlUh35nCLSkQTiQ8fbUzmNtq2iEGLkXdysImJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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