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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c971c2267e4197b1d0f0046d6015d134fd9c6b838a5299cf12747cbb6353df6' 
  AND token = '0szm+9cvhf9pUOa6SMcUvrFomSJSVDNXvboa6juSCEc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}