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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cd9e5c1d8a2ebf7b31a8c3e32687c6f02a0a268047f3e0d827f3e9a0914a455' 
  AND token = '+Uucsde/lMG8RpL1OFfWasfQ0YU4+1uCWA8lnJT9IaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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