SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1df75ed83d3c417184cfbc2d01002ddb4b68f6412a9245eac0dc39735ed521c' 
  AND token = 'lyj7XTIfncYsITvADpRL+sSP7wXZAm8zKKufehtlDuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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