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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a0bbb3146cf13971103229a19b9d0b4e9c473d5626215606e0e22f4d56dba52' 
  AND token = 'ZYCK/Xig30W7FFbn7kSObPSFUe9GNN1c8+PQGAi1ecs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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