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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75b791f209ffa9d0c259ccb0f1841c55e57b2b67f9bccd3dfde6ff5bd5139b7c' 
  AND token = 'G7ReBxOEYrBti1iq3+yHciJrcMS+iAJAkxWIyZNkdKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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