SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ae236eec996aad0bdf2774c925e4d8be39d4375f7bceb535105e306ca10e6a5' 
  AND token = '6WmOgNWmpRX83DfG8w3vXmTeCvsKBrfiUO30sRnAuao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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