SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39604d3a17727b1ba2dfb07ad66f4da58b0a58a70483ecded85adda1c01cbb48' 
  AND token = 'abA3PWffnTATTn5vzPz2QSDP7WEiSYCCqhKyJQCO+ag=' 
  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"
    }
  }
}