SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd923c2ee79083a6dfbe0b5ba8374a7c67f68702ea7710b508da7d1667240eb27' 
  AND token = 'zs1zxC2ZoUhtHnaa342l3veOexEK/GE/0Ex+/YPIDxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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