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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0a1fdebe17dcb5cba2dc8deac13abd98c84bb968b72fd35c487e2ae303d6f20' 
  AND token = 'nqq2jazZB9Fli4o3MzmLan5U+NKwT8xaCAzu8KhL6Yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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