SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f6e1d05385270e65abf43cf451683af7613288020a0c39769b3e385956a18d9' 
  AND token = 'Qnj54LTV74ZMm6gp4V758AinJkrYxRRw6LncZqym8M8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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