SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fb16728a71789a2f8d5e59d75b718cd7871898d0dd956bdede8aa447422cbc3' 
  AND token = 'uRlssiWaMmTGJn/lIDaEhU3z3/UH5+Ym6DNw4UIaRGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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