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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdb5f9edbbe53e24527fe2fe8b7ab00044cd15f9cc3c7239c88f9e72abf0cf9c' 
  AND token = 'v4nTveJ2NVVg5BiAt+BRghMBKSZHCYaD305an2KttJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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