SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '376f0e9e4beefe15a6c5751113339966d3fda263f126fe71fc861a5476ba9c98' 
  AND token = '3l3ItKPIVlrnUJ8hiHIjVCA/sfa+ln9kHKnPz847ua8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}