SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f6429ad2bd216c5328e524593fedab87015541734f04dfc20a08b4822167f7e' 
  AND token = 'Lh7ezhhvYJR9vmxg4A0yWLw+T/tzSEd+BNSemkELAA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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