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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '278244a0a2287fcfadeb67f829e3d8dcd0046c788c419f2e034e3a26ba1a262d' 
  AND token = 'vVrsvbjbcM4pstHvR3vF2FIfs/zxe5wPJwkfQOAhhBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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