SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0794ddd7e2ec75a479659c91b1808b3e1be9f612771dee76a44883376f5fbf7f' 
  AND token = 'k7FrUP2rbZow+rRWL3wxU8/CmVGLtJcIAxKMpRN0Awg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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