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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31c5f5574110a8681fb09c3f80615c017a00c4f70496181b8ca7d5225f0c8ca3' 
  AND token = 'Fsat+n1ijPl0OWCQxjkbWv79DUnlO4qKJDjgivS9FSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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