SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff803522a275714be36446b4623f0d30eac593876a93fcb5f84f2ae36b255fec' 
  AND token = '0aiPCp24++DrZCMgjAdlf4GVrBy46IeGBG9bOHoluz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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