SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e45ffecf9e2cbfe7f844b2a62d70a413f2252f41e4c42432cce2de93929fdc1' 
  AND token = 'tMkgAM2lNKdp5VEJ7rtPzIlajhYtuRBRageSLK+2AvM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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