SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19c6bb0a421af8033d413990167573067d096849f3dfa3fad2a8b955de4fbb89' 
  AND token = 'LLztIVhETLhgCOQB5mtQIzGYsZ2BB2Ya+oeoOPHMh4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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