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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b9bc29a6b995f2b644ab6d0585fce4edc6fc2452ee8cc89a9dd84e7a8872fa' 
  AND token = 'oqP1BmNH5Gf2PBm4mcvLQOf0u61fBB7Rw1vt47lDCLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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